Research Affiliates: “True Grit: The Durable Low Volatility Effect”

In the latest piece from Research Affiliates, Feifei Li, Director and Head of Product Research & Management, and Philip Lawton, Vice President, Marketing, look at reasons why low-risk stocks outperform high-risk stocks in the long run, which is counter to the generally accepted investment tenet that one must accept higher risk to earn higher returns.

True Grit: The Durable Low Volatility Effect

One of the basic tenets of finance is that investors are compensated for taking risk. For equity markets, that means that high volatility stocks are expected to outperform low volatility stocks. But that hasn’t happened. Low-risk stocks have historically outperformed high-risk stocks.

Will this low volatility effect persist? Renewed interest in low volatility strategies has led to higher demand for low volatility stocks, and high demand for low volatility stocks could conceivably eradicate the return premium once and for all. Nonetheless, the effect has proven robust across time periods and markets, and, unless contrarian investing paradoxically becomes the norm, there is good reason to believe that it won’t go away anytime soon.

Historical Record

The low volatility effect has been known so long1 and studied so extensively that there is little danger it will be discredited as a statistical fluke or a by-product of incomplete or erroneous data. Low volatility stocks tend to trade at a discount to the broad market and, of course, to high volatility stocks; the magnitude of the discount is highly variable,2 but the low volatility effect has nonetheless been durable (see Table 1). The fact that simulated low volatility strategies have produced excess returns in many countries implies that the effect is deeply embedded in global capital markets.

The historical record, then, is reassuring. Nonetheless, we’ve all seen rapid, even cataclysmic, change in other situations. Institutional arrangements can break down, technological advances can disrupt the balance of power, regulatory reforms can impede capital flows or raise the cost of trading, and, in principle, people can learn from experience. Even if we resolutely assume that radical change is unlikely, we cannot offer an opinion on the continuance of the low volatility effect without understanding the conditions that have made it possible thus far.

Revisiting Risk and Return

Riskier assets have higher expected returns. That statement might be considered too categorical in academic circles, but it is an article of faith in active portfolio management. Investors are rewarded by profits for risking their capital just as hourly workers are compensated by wages for committing their bodies and minds to economically productive activities. And, considering that wage-earners get more pay for putting in longer days, investors quite reasonably require higher rewards for taking on more risk. John Stuart Mill (1885, p. 107) vividly expressed the idea: “The profits of a gunpowder manufacturer must be considerably greater than the average, to make up for the peculiar risks to which he and his property are constantly exposed.” Rates of return are a straightforward function of risk, and rational investors set their expectations accordingly.

The theoretical relationship between ex ante risk and expected return is so obviously a truism that it seems silly to write about it. But we bring it up here precisely because it “goes without saying.” The statement that one must accept higher risk to earn higher returns is axiomatic. It is, in fact, such a basic proposition that classical and neoclassical finance simply cannot be stretched or twisted to accommodate contrary observations. Calling the low volatility effect an “anomaly” implies it’s reasonable to hope for an as-yet undiscovered explanation that is consistent with the standard model.